Accumulator

ABSTRACT

An accumulator comprises at least one galvanic cell and a receiving device for supporting the galvanic cell(s) of the accumulator. The receiving device comprises at least one protecting wall for receiving energy by means of elastic and/or plastic deformation. The protecting wall encases the at least one galvanic cell at least partially and has a thickness which is at least partially less than about 1/10 of the characteristic edge length of the at least one galvanic cell. This Abstract is not intended to define the invention disclosed in the specification, nor intended to limit the scope of the invention in any way.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 of GermanPatent Application No. 10 2008 047 615.3, filed Sep. 17, 2008, theentire disclosure of which is expressly incorporated by referenceherein.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention refers to an accumulator. The invention isdescribed with respect to lithium-ion accumulators to supply thedrivetrain of motor vehicles. The invention may be used independent ofthe type of the accumulator or independent of the type of the drive.

2. Discussion of Background Information

Accumulators for supplying the drivetrain of motor vehicles are known.Some of these types of accumulators share the feature that theirgalvanic cells are not sufficiently protected against damaging.Accordingly, it would be advantageous to be able to protect anaccumulator or its galvanic cells against mechanical damaging with anadequate protecting device.

SUMMARY OF THE INVENTION

The present invention provides an accumulator which comprises at leastone galvanic cell and a receiving device for holding the at least onegalvanic cell. The receiving device comprises at least one protectingwall for absorbing energy by means of elastic and/or ductiledeformation. The at least one protecting wall surrounds the at least onegalvanic cell which is held by the receiving device at least partiallyand has a thickness which is at least in parts less than about 1/10 ofthe characteristic edge length of the at least one galvanic cell.

In one aspect, at least one protecting wall may surround the at leastone galvanic cell which is held by the receiving device at leastpartially and with positive locking.

In another aspect, the at least one galvanic cell may comprise agas-tight jacket and the at least one protecting wall may be capable ofabsorbing more strain energy than the gas-tight jacket.

In another aspect, the at least one protecting wall may comprise atleast one first material which is electrically non-conducting at avoltage which is similar to the nominal voltage of the accumulatorand/or may comprise at least partially a covering layer. For example,the at least one first material may comprise at least one curablepolymer. Further, the at least one first material may be capable offorming cavities during curing.

In another aspect of the accumulator of the present invention, thedensity of the at least one protecting wall may be less than about 1,500kg/m³, e.g., less than about 150 kg/m³, or less than about 15 kg/m³and/or the density of the at least one protecting wall may be higherthan about 5 kg/m³.

In yet another aspect, the at least one first material of the at leastone protecting wall may further comprise at least one filler materialwhich is able to at least partially join with the cured first materialby material engagement and the cured first material may at leastpartially surround the at least one filler material, and the cured firstmaterial with the filler material may show a larger Young's modulusand/or a larger tensile strength than the cured first material withoutthe filler material.

In a still further aspect, the at least one protecting wall may furthercomprise at least one second material which has a larger thermalconductivity than the at least one first material and is capable ofpassing through a phase change at predetermined conditions, at leastpartially, which second material may show a larger absorptivity withrespect to the electrolyte of the galvanic cell than the at least onefirst material and/or may form at least one channel which may bepermeable.

In another aspect, the at least one protecting wall may further comprisefilling particles, the density of which is lower than the density of theat least one first material.

The present invention also provides a method of manufacturing theaccumulator of the present invention as set forth above (including thevarious aspects thereof). The method comprises at least

-   -   (a) arranging the at least one galvanic cell in a mold        corresponding to the shape of the accumulator; and    -   (b) filling the mold, at least partially, with a material for        forming the at least one protecting wall.

In one aspect of the method, at least one further substance may be addedto the material for use in (b) for affecting a viscosity of the uncuredmaterial for forming the at least one protecting wall.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described in the detailed descriptionwhich follows, in reference to the noted plurality of drawings by way ofnon-limiting examples of exemplary embodiments of the present invention,in which like reference numerals represent similar parts throughout theseveral views of the drawings, and wherein:

FIG. 1 shows a sectional view of an accumulator according to the presentinvention; and

FIG. 2 shows an enlarged section of the protecting wall 3.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

The particulars shown herein are by way of example and for purposes ofillustrative discussion of the embodiments of the present invention onlyand are presented in the cause of providing what is believed to be themost useful and readily understood description of the principles andconceptual aspects of the present invention. In this regard, no attemptis made to show structural details of the present invention in moredetail than is necessary for the fundamental understanding of thepresent invention, the description taken with the drawings makingapparent to those skilled in the art how the several forms of thepresent invention may be embodied in practice.

An accumulator according to the present invention comprises at least agalvanic cell and a receiving device. The receiving device is intendedto hold the galvanic cells of the accumulator. The receiving devicecomprises at least a protecting wall. This protecting wall is intendedto absorb energy by means of elastic and/or ductile deformation. Atleast partially, the protecting wall surrounds the at least one galvaniccell which is held by the receiving device. The thickness of theprotecting wall is at least partially less than about 1/10 of thecharacteristic edge length of the at least one galvanic cell held by thereceiving device.

The present accumulator is an apparatus intended to store energy. Theenergy is stored as chemical energy in the at least one galvanic cell ofthe accumulator. To supply an electrical drive, chemical energy is atfirst converted to electrical energy. During a charging process of theaccumulator the conversion of electrical energy to chemical energy isexecuted in the opposite direction.

The present accumulator comprises at least one galvanic cell. Theconstruction of a galvanic cell is commonly known and thus is notexplained here. To explain the mode of action of the invention it shallsuffice to state that the galvanic cell also includes an electrolyte.Also, a galvanic cell is usually surrounded by a gas-tight jacket. Thisjacket serves to prevent the galvanic cell from the influx of water orsteam. To achieve this, the jacket is usually designed to be a gas tightfilm, at least partially, for instance to be a metal film.

The present accumulator comprises a receiving device. This device isalso intended to support the at least one galvanic cell of theaccumulator. Supporting shall be understood to mean that the at leastone galvanic cell of the accumulator remains within the combination ofthe accumulator and its further components during the intended use ofthe accumulator.

The present receiving device comprises at least one protecting wall. Theprotecting wall serves the purpose to prevent the at least one galvaniccell of the accumulator from mechanical damaging, too. So the protectingwall or its material are intended to absorb impacting mechanical energythrough elastic and/or ductile deformation and to hold mechanical energyoff the at least one galvanic cell, for example. An elastic deformationis preferably inverted after consuming the impacting mechanical energy.Depending on the sort and amount of mechanical energy or the sort of thebody carrying said energy, the elastic deformability of the protectingwall may not suffice. The protecting wall is designed to also absorbmechanical energy through ductile deformation. So, a body carryingenergy or being loaded with a force will intrude into the protectingwall by a certain distance and will displace its material. This mayresult in a breaking of the protecting wall. The energy absorbed in sucha way is not available to further damaging the accumulator or itsgalvanic cells. Also, the impacting mechanical energy is spread onto alarger surface by the protecting wall.

Kinetic or potential energy presently acts on the accumulator through athrust or blow or through a force. This will act on the accumulator or agalvanic cell through an arbitrary body over a time interval and/or acertain distance.

At least partially, the protecting wall surrounds the at least onegalvanic cell. Economical considerations of material usage and cost ofmanufacturing, available space, design of the accumulator, number orarrangement of several galvanic cells, if applicable, site of operationof the accumulator, kind and extent of the expected damaging effects andother conditions will define the extent by which the protecting wallsurrounds the at least one galvanic cell. Only one of several boundarysurfaces of an accumulator may feature a protecting wall.

The thickness of the protecting wall is chosen depending on the expectedperil, the weight of the accumulator or the material used for theprotecting wall. To maintain a desired specific power or energy withrespect to volume or weight of the accumulator, the protecting wall ischosen to be as thin as possible. The protecting wall is chosen to be asthick as necessary to provide the protection required. The thickness ofthe protecting wall is chosen depending on the load and need not beuniform. The thickness of the protecting wall is to be chosen inrelation to the characteristic edge length. Preferably, the thickness ofthe protecting wall is at least partially less than about 1/10 of thecharacteristic edge length of the at least one galvanic cell held by thereceiving device, preferably less than about 1/25 of this characteristicedge length. Alternatively, the thickness of the protecting wall isdimensioned in mm. Preferably, the thickness of the protecting wall isat least partially from about 0.01 mm to about 100 mm, preferably fromabout 0.1 mm to about 20 mm, most preferred from about 0.5 mm to about10 mm.

The characteristic edge length of a galvanic cell is a reference size.It is calculated as the mean average of the lengths of the edges of thegalvanic cell and accounts for the geometry of the galvanic cell. Forinstance, in case of a block-shaped galvanic cell, the three differentlengths of edges of the rectangular block are used. In case of acylindrical cell or a rotationally symmetric cell, the lengths along therotational axis and the radius of the base area are used. In case of aprismatic cell with arbitrary base area, a substitute body with the samevolume is defined, at first. Its circular base area has the same surfacearea as the base area of the prism. Then the length of the rotationalaxis and the radius of the substitute base area are used, similar to thecase of the cylindrical cell. Usually, several uniform galvanic cellsare processed to an accumulator. Otherwise, the mean average of thecharacteristic edge lengths of the different galvanic cells is to bedefined and to be used. Presently, the dimension defined in this manneris to be understood as the “mean characteristic edge length”. In thiscase, the mean characteristic edge length is to be used in lieu of thecharacteristic edge length.

By design of an accumulator or its receiving device according to theinvention with a protecting wall, occurring damaging mechanical loadsmay be held off the galvanic cells of the accumulator. So, theaccumulator is prevented from damaging and the underlying aim is met.Further advantages of the invention can be taken from the followingnon-limiting embodiments.

Advantageously, the protecting wall surrounds at least partially the atleast one galvanic cell held by the receiving device by positivelocking. The degrees of freedom of motion of a galvanic cell aresignificantly reduced by surrounding with positive locking. Thereby, theprotecting wall abuts tightly on the at least one galvanic cell. If theaccumulator comprises a plurality of galvanic cells, which are arrangedside by side and in a row in close contact similar to rows and columnsof a table, the degrees of freedom of motion of the galvanic cellsarranged inside are limited by their neighbors. Thereby, the protectingwall imposes elastic restoring forces on to the galvanic cellssurrounded with positive locking, preferably. Preferably, the at leastone galvanic cell is at least partially encapsulated by this protectingwall. So, good positive locking is achieved between the protecting walland the at least one galvanic cell of the accumulator. This is done tosave space, to hold the at least one galvanic cell within the receivingdevice and to prevent the accumulator from damaging through vibrations.This is achieved by choosing an appropriate material for the protectingwall and the design of the protecting wall. So, the protecting wallpreferably shows high internal friction. This helps to absorb impactingenergy from vibrations, too. The protecting wall surrounds the at leastone galvanic cell to protect against moisture, corrosion and otherdamaging substances. After a failure of a galvanic cell, it may beremoved from this receiving device and may be replaced, advantageously.

Advantageously, a galvanic cell comprises a gas tight jacket. This istrue in case of using an electrolyte with lithium ions. To aid this, thegas tight jacket may be manufactured from a metal film, for instance.The protecting wall is able to absorb more strain energy than the gastight jacket by choosing an appropriate wall thickness and material. Tothis end, the protecting wall preferably comprises stays and/orreinforcing ridges. The term ‘strain energy’ as well as methods for itscalculation are defined in the literature concerning engineeringmechanics.

Advantageously, the protecting wall also acts to isolate electrically.To this end the protecting wall comprises a first material. Theprotecting wall acts to isolate electrically at voltages similar to thenominal voltage of the accumulator. Most preferred, the protecting wallacts to isolate electrically at voltages which are equal to severaltimes the nominal voltage of the accumulator. This is achieved bychoosing an appropriate first material for the protecting wall. To thisend, expected voltages need to be considered. Preferably, the firstmaterial isolates electrically at a voltage which is equal to about 10times the nominal voltage of the accumulator, most preferred equal toabout 100 times the nominal voltage of the accumulator.

Preferably, the protecting wall is equipped with at least one coveringlayer, at least partially. The at least one covering layer is arrangedon an outside surface of the protecting wall. For instance, a coveringlayer is arranged on an inside surface of the protecting wall, whereinthe inside surface faces the galvanic cell(s) of the accumulator.Optionally, the outer surface of the protecting wall is equipped with acovering layer. Preferably, the protecting wall comprises a coveringlayer in regions which are exposed to particular wear, to avoid grit,for instance. Depending on the selection, the covering layer will actagainst chemical and/or thermal exposure, preferably. The covering layeracts in a flame-retarding manner, for instance. In case of a fire, sucha covering layer may expand and/or produce foam, carbonize or become aceramic. Preferably, a protecting wall comprises several differentcovering layers at the same time.

Advantageously, the first material of the protecting wall is a curablepolymer. Preferably, polymers are chosen which can be manipulatedeasily, show low density, high ability to absorb energy, high ability toisolate electrically. Optionally, the first material may be a mixture ofmaterials depending on what the protecting wall is subjected to.Preferably, a copolymer is chosen to form the first material to adaptthe material properties to the expected exposures. The first materialmay be pretreated depending on the requirements of processing, ifneeded. For instance, the polymer may be chosen from a group includingunsaturated polyester (UP), epoxy (EP), polyamides, polystyrenes.

Advantageously, the first material comprises cavities after curing.Preferably, the cavities are filled with a gas. The cavities aresurrounded by a joisting of the first material. Compared to the solidfirst material, the first material with cavities shows higher values ofmoment of inertia, of bending stiffness, of density, of ability toabsorb energy and/or of reversible deformation or of elastic strain.Preferably, the diameter of a substitute body of a cavity with similarvolume is less than about ⅕ of the thickness of the protecting wall.Preferably, the cavities are distributed within the first material asevenly as possible. So, the protecting wall with a cured first materialwith cavities gains thickness and protective effect, too, while thespecific power or energy with respect to volume and weight diminishesinsignificantly.

The structure of the protecting wall may be compared to a frozen foam.This frozen foam of low density is able to bear a high bending load or ahigh impact loading in comparison. Depending on the material used andthe curing conditions, the frozen foam may comprise various Young'smoduli or permitted values of elastic strain. So the protecting wallwill absorb energy through elastic or ductile strain while showing a lowweight. This is also known from foamed plastic or metal foam.

Optionally, an auxiliary substance may be added to the first material.This auxiliary substance may expand at predetermined conditions,preferably before or while curing of the first material. Preferably, theauxiliary substance acts to improve foaming of the first material, forexample as a propellant, acts to improve cohesion of the solid phase ofthe protecting wall, to improve curing of the participating polymersand/or to increase long term stability of the cured first material.Preferably, the at least one auxiliary substance is able to form agaseous phase at predetermined conditions. In doing so, the gaseousphase is created as a result of a phase change of the auxiliarysubstance and/or as a result of a chemical reaction of the auxiliarysubstance while creating a gas, preferably. Preferably, the gaseousphase remains contained within the cavities of the cured material.

Preferably, the protecting wall is designed to be lightweight. Itsdensity is less than about 1,500 kg/m³, preferably less than about 150kg/m³, most preferred less than about 15 kg/m³, and more than about 5kg/m³. So, the high specific power of the accumulator is maintained withrespect to volume or weight. To this end, cavities are useful which arepreferably filled with gas and are enclosed within the protecting wall.

Preferably, the first material (4) of the protecting wall (3) furthercomprises at least one filler material. It is capable of materialengagement with the cured polymer of the first material (4), at leastpartially. Thereby the cured polymer surrounds this filler material, atleast partially. This filler material acts such that the first material(4) after curing with the filler material features a higher Young'smodulus and/or higher permitted values of elastic strain. Preferably,the filler material comprises a plurality of short rods or fibers,though other geometries are possible. These rods or fibers may be eitherarranged without order and distributed or are arranged as a woven fabricor a laid layer within the cured first material. Thereby, several layersof woven fabrics or laid layers may be put one upon the other withdifferent directions of the fibers. The presence of the filler materialalters the properties of the first material (4). When compared with thepolymer of the first material (4), the fibers show increased Young'smodulus and/or permitted values of elastic strain in their axialdirection. Depending on the arrangement of the fibers, the cured firstmaterial can be set up to have different material properties withrespect to the axes of a Cartesian coordinate system. The rods or fibersmay be made from glass, carbon or an aramide, for instance.

Preferably, the protecting wall further comprises a second material. Thesecond material shows a larger thermal conductivity than the firstmaterial, preferably. For instance, aggregations show predeterminedshapes, such as wire sections, films, a net, woven fabrics, non-wovenfabrics, rounded geometries like beads, films or strips of film.Preferably, such aggregations are arranged within the protecting wall inan aligned manner and are inserted during the manufacturing of theprotecting wall. So, thermal energy may be added or removed. Preferably,the second material passes through a phase change at predeterminedconditions to absorb or release thermal energy. These predeterminedconditions are chosen depending on the operating conditions of theaccumulator. Preferably, the second material is arranged in rounded,distributed aggregations. The diameter of a ball shaped substitute bodywith a volume similar to the volume of an aggregation is less than halfthickness of the protecting wall, preferably less than about 1/10 of itsthickness.

There is a variation of the volumes of several aggregations of thesecond material within a range, which offers advantages with respect totheir application and the cost of manufacturing. Preferably, the secondmaterial shows a higher absorptivity with respect to the electrolytethan the first material. Emerging electrolyte may be absorbedparticularly by the second material after damage to the jacket of agalvanic cell. In doing so, the proximity is protected from theelectrolyte.

Preferably, the second material is designed to be at least one solidbody, forming a channel. The channel of this solid body may accept acooling agent or may be passed through by a cooling agent. So, thermalenergy may be delivered or dissipated. Preferably, the second materialacts flame-retarding. For instance, the second material may expandand/or produce a foam during a fire, carbonize or convert to a ceramic.The damaging effects of a fire upon the proximity of the accumulator mayat least be reduced in this manner.

An advantageous embodiment of the protecting wall (3) further comprisesseveral filling particles. The shape of a filling particle mainlyresults from the outcome of the manufacturing of the filling particle.It is not compulsory that the filling particles have the same shape. Forinstance, the filling particles may show a ball-shaped, an ellipsoidic,a drop shaped or any other geometry which is mainly rotationallysymmetric. The mean diameter of a filling particle, which isalternatively determined by measuring a ball of similar volume(substitute body), is within a range of from about 0.01 to about 5,000microns, preferably from about 0.1 to about 1,000 microns, mostpreferably from about 1 to about 400 microns. The mean diameters of thefilling particles scatter about an averaged mean diameter of a multitudeof filling particles. Preferably, the filling particles arepredominantly hollow and/or show closed surfaces. The density of afilling particle preferably is less than the density of the cured firstmaterial. Preferably, the filling particles comprise at least one solidmaterial such as glass or plastic, for instance.

A mold and at least one material are required to manufacture a receivingdevice of the accumulator according to the present invention. The atleast one galvanic cell of the accumulator is arranged within the mold.Usually, the accumulator comprises a multitude of galvanic cells whichare electrically connected by serial connection/parallel connection. Inthis case, all galvanic cells of the accumulator are arranged within themold. Within the mold, the galvanic cells are prevented from unintendeddisplacement against each other with spacers or with the help of anauxiliary device from outside the mold, for instance. Extra necessarydevices of the accumulator may be arranged within the mold. Next, thedesignated chambers in the mold are at least partially filled with thematerial for forming the protecting wall. If the protecting wall has toinclude further materials or parts, they are added to designatedchambers of the mold.

Optionally, the galvanic cells and the produced protecting wall remainin the mold. Then the mold becomes the casing of the accumulator. Inthis case, the shape of the mold, i.e. its material or its geometry, isadapted to the requirements of the operation of the accumulator, too. Inthis case, the mold may have one or more parts, may be made from metaland/or plastic, may be equipped with devices to connect to the motorvehicle, and may be designed with openings to lead in electric cablesand/or other supply lines.

Optionally, a further substance may be added to the material for formingthe protecting wall, whereby the viscosity of the mixture is alteredwith respect to the uncured material. In doing so, the flowability ofthe first material is affected during its processing to become theprotecting wall. Preferably, the further substance is a powdery solidmatter, most preferably Aerosil®. Also, a different solid matter may beused as further substance, if the viscosity of the pourable mixture ofthe further substance and said material is to be different from theviscosity of said material.

FIG. 1 shows a sectional view of an accumulator according to the presentinvention. This accumulator comprises four galvanic cells 1 in serialconnection plus a receiving device 2. The serial connection of thegalvanic cells 1 is symbolized by three bridges and two pins on theupper ends of the galvanic cells 1. The receiving device 2 is providedwith a protecting wall 3. The cross section of this protecting wall 3 isdepicted to the left and to the right of the galvanic cells 1. Thethickness of the protecting wall 3 is dimensioned to be less than atenth of the mean characteristic edge length of the galvanic cells 1held. Pre-foamed and aeriferous beads 4 made of polystyrene serve asfirst material of the protecting wall 3. The beads 4 are expanded withthe help of hot steam. Thereby, the air contained by the beads expands,the beads increase to become balls. The present balls 4 of polystyreneconnect to each other. The polystyrene 4 expanded in this manner has adensity of about 70 kg/m³, for instance. The design of the protectingwall 3 is depicted in FIG. 1 schematically, only. In fact, thepolystyrene forms the walls of the balls 4 and their inner bars. Thevoids between the bars of a ball 4 are filled with air. The massfraction of the polystyrene is negligible. By choosing polystyrene asfirst material 4, the protecting wall 3 is not electrically conductivewith respect to the nominal voltage of the accumulator, i.e., 12V. Thesmall density of the protecting wall 3 causes the specific power orenergy of the accumulator with respect to volume of weight not todecrease significantly.

The protecting wall is produced by using pre-foamed aeriferous beads 4from polystyrene and a mold. At first, the galvanic cells 1 of theaccumulator are arranged within the mold and are jammed against eachother to avoid undesired displacements. Next, the beads 4 are added todesignated chambers within the mold. During the following step, the moldwith its content is exposed to the conditions required to expand thebeads. The beads 4 are exposed to hot steam, thereby. The beads 4 willexpand and fill the designated chambers to fix the galvanic cells 1.Thereby, the galvanic cells 1 are surrounded by foam only by as much asto leave the electrical contact surfaces of the galvanic cells toprotrude from the protecting wall 3. In a further step the accumulatormay be removed from the mold and the mold may be reused. After theirfailure, individual galvanic cells 1 may be removed from the receivingdevice 2 and may be replaced.

The mold of this embodiment also forms the casing of the accumulator.The casing is provided with corresponding means for connection andopenings. Also the casing is adapted to being installed in the motorvehicle with respect to its shape. The casing also offers extraprotection of the accumulator. The casing is made from steel plate,which is folded and welded. The casing may also be manufacturedentirely/partially from plastic or may be manufactured with othermanufacturing methods, too.

Alternatively, the designated mold is first filled with a first material4. The galvanic cells 1 are connected to a supporting unit, which is anauxiliary production means, which supports the galvanic cells 1 againstone another immovably. Then the galvanic cells 1 are dipped into thefirst material 4. The supporting unit is connected to the mold. Theprocesses of expanding and curing of the first materials 4 follow.Afterwards the galvanic cells 1 are not entirely surrounded by theprotecting wall 3.

FIG. 2 shows an enlarged detail of the protecting wall 3 of a furtherembodiment. The protecting wall 3 shows an expandable polymer 4 and asecond material 7 with high thermal conductivity, both serving as firstmaterial. The second material 7 features a significantly larger thermalconductivity than the first material 4. The second material 7 isdesigned to have oblong, irregular strips. By its shape and design, thesecond material 7 contributes to remove thermal energy from a galvaniccell 1 contacting the protecting wall 3.

Another second material 7 a passes through a phase change atpredetermined conditions. The second material 7 a forms solid matter ata predetermined temperature of the accumulator. The second material 7 ais chosen such that its melting temperature exceeds the predeterminedoperating temperature of the accumulator only by a small margin. If thetemperature of a galvanic cell 1 in contact exceeds the meltingtemperature of the second material 7 a, it passes through a phase changeand becomes a liquid, partially. The aggregation of the second material7 a will keep the melting temperature until it has been entirelyconverted to a liquid. In doing so, the aggregation of the secondmaterial 7 a absorbs thermal energy and contributes to cooling agalvanic cell 1 in contact.

It is noted that the foregoing examples have been provided merely forthe purpose of explanation and are in no way to be construed as limitingof the present invention. While the present invention has been describedwith reference to exemplary embodiments, it is understood that the wordswhich have been used herein are words of description and illustration,rather than words of limitation. Changes may be made, within the purviewof the appended claims, as presently stated and as amended, withoutdeparting from the scope and spirit of the present invention in itsaspects. Although the present invention has been described herein withreference to particular means, materials and embodiments, the presentinvention is not intended to be limited to the particulars disclosedherein; rather, the present invention extends to all functionallyequivalent structures, methods and uses, such as are within the scope ofthe appended claims.

1. An accumulator, wherein the accumulator comprises at least onegalvanic cell and a receiving device for holding the at least onegalvanic cell, which receiving device comprises at least one protectingwall for absorbing energy by means of at least one of elastic andductile deformation, the at least one protecting wall surrounding the atleast one galvanic cell which is held by the receiving device at leastpartially and having a thickness which is at least partially less thanabout 1/10 of a characteristic edge length of the at least one galvaniccell.
 2. The accumulator of claim 1, wherein the at least one protectingwall surrounds the at least one galvanic cell which is held by thereceiving device at least partially and with positive locking.
 3. Theaccumulator of claim 1, wherein that the at least one galvanic cellcomprises a gas-tight jacket and wherein the at least one protectingwall is capable of absorbing more strain energy than the gas-tightjacket.
 4. The accumulator of claim 1, wherein the at least oneprotecting wall at least one of (i) comprises at least one firstmaterial which is electrically non-conducting at a voltage which issimilar to the nominal voltage of the accumulator and (ii) comprises atleast partially a covering layer.
 5. The accumulator of claim 4, whereinthe at least one first material comprises at least one curable polymer.6. The accumulator of claim 5, wherein the at least one first materialis capable of forming cavities during curing.
 7. The accumulator ofclaim 1, wherein a density of the at least one protecting wall is lessthan about 1,500 kg/m³.
 8. The accumulator of claim 1, wherein a densityof the at least one protecting wall is less than about 150 kg/m³.
 9. Theaccumulator of claim 1, wherein a density of the at least one protectingwall is less than about 15 kg/m³.
 10. The accumulator of claim 1,wherein a density of the at least one protecting wall is higher thanabout 5 kg/m³.
 11. The accumulator of claim 4, wherein the at least onefirst material of the at least one protecting wall further comprises atleast one filler material which is able to at least partially join withthe cured first material by material engagement and the cured firstmaterial at least partially surrounds the at least one filler material,and wherein the cured first material with the filler material shows atleast one of a larger Young's modulus and a larger tensile strength thanthe cured first material without the filler material.
 12. Theaccumulator of claim 4, wherein the at least one protecting wall furthercomprises at least one second material which has a larger thermalconductivity than the at least one first material and is capable ofpassing through a phase change at predetermined conditions, at leastpartially, which second material at least one of (i) shows a largerabsorptivity with respect to an electrolyte of the galvanic cell thanthe at least one first material and (ii) forms at least one channelwhich may be permeable.
 13. The accumulator of claim 4, wherein the atleast one protecting wall further comprises filling particles, a densityof which is lower than a density of the at least one first material. 14.The accumulator of claim 12, wherein the at least one protecting wallfurther comprises filling particles, a density of which is lower than adensity of the at least one first material.
 15. A method ofmanufacturing the accumulator of claim 1, wherein the method comprisesat least (a) arranging the at least one galvanic cell in a moldcorresponding to a shape of the accumulator; and (b) filling the mold,at least partially, with a material for forming the at least oneprotecting wall.
 16. The method of claim 15, wherein at least onefurther substance is added to the material for use in (b) for affectinga viscosity of the uncured material for forming the at least oneprotecting wall.